It is widely acknowledged that high levels of cholesterol can lead to cardiovascular disease. In recent years, the need to maintain a healthy level of serum cholesterol has become increasingly important. However, many individuals find that this is only possible through the use of cholesterol-lowering agents. Several trials of the long-term effects of cholesterol-lowering drugs on patients have shown reduced death from and incidence of heart disease. (See Lipid Research Clinics Investigators, Arch Intern Med 152:1399-1410 (1992)). However, some long-term studies on cholesterol lowering have suggested that very low cholesterol levels in an individual may be associated with an increased risk of cancer death. (J. A. Heady, WHO Clofibrate/Cholesterol Trial: Clarifications, The Lancet 340:1405-1406 (1992); The Helsinki Heart Study, JAMA 260:641-665 (1988); and The Helsinki Heart Study 8.5 year cumulative update (1992)).
There is compelling evidence that oxidized low-density lipoprotein (LDL) plays an important role in the formation of artherosclerotic lesions. (Chisolm, Clin. Cardiol. 14:I-25 - I-30 (1991)). As LDL becomes oxidized, its properties and mechanisms of interaction with cells are altered extensively. These changes cause the oxidized LDL to act deleteriously at various levels of artherosclerotic lesion development. Recent studies have shown that taking antioxidants such as vitamin E or beta carotene, reduces an individual's risk of heart attack presumably by preventing the oxidation of LDL (See NY Times, p. A9, cols. 1-6, Nov. 19, 1992). In addition, studies have shown that individuals who have low plasma levels of antioxidants have an elevated risk of cancer. Stahelin et al., Am J Epidemiology 133:766-775 (1991); Potischman, et al., Nutr. Cancer 15:205-215 (1991).